scholarly journals N-Hydroxyarylamine O-Acetyltransferases Catalyze Acetylation of 3-Amino-4-Hydroxyphenylarsonic Acid in the 4-Hydroxy-3-Nitrobenzenearsonic Acid Transformation Pathway of Enterobacter sp. Strain CZ-1

2019 ◽  
Vol 86 (2) ◽  
Author(s):  
Ke Huang ◽  
Fan Gao ◽  
X. Chris Le ◽  
Fang-Jie Zhao
Keyword(s):  
Growth Promotion ◽  
Functional Characterization ◽  
Major Product ◽  
Site Directed Mutagenesis ◽  
Feed Additive ◽  
Pcr Analysis ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Arsanilic Acid ◽  
Relative Expression Level

ABSTRACT The organoarsenical feed additive 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone [ROX]) is widely used and released into the environment. We previously showed a two-step pathway of ROX transformation by Enterobacter sp. strain CZ-1 involving the reduction of ROX to 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) and the acetylation of 3-AHPAA to N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA) (K. Huang, H. Peng, F. Gao, Q. Liu, et al., Environ Pollut 247:482–487, 2019, https://doi.org/10.1016/j.envpol.2019.01.076). In this study, we identified two nhoA genes (nhoA1 and nhoA2), encoding N-hydroxyarylamine O-acetyltransferases, as responsible for 3-AHPAA acetylation in Enterobacter sp. strain CZ-1. The results of genetic disruption and complementation showed that both nhoA genes are involved in ROX biotransformation and that nhoA1 is the major 3-AHPAA acetyltransferase gene. Quantitative reverse transcription-PCR analysis showed that the relative expression level of nhoA1 was 3-fold higher than that of nhoA2. Each of the recombinant NhoAs was overexpressed in Escherichia coli BL21 and homogenously purified as a dimer by affinity chromatography. Both purified NhoAs catalyzed acetyl coenzyme A-dependent 3-AHPAA acetylation. The Km values of 3-AHPAA for NhoA1 and NhoA2 were 151.5 and 428.3 μM, respectively. Site-directed mutagenesis experiments indicated that two conserved arginine and cysteine residues of each NhoA were necessary for their enzyme activities. IMPORTANCE Roxarsone (ROX) is an organoarsenic feed additive that has been widely used in poultry industries for growth promotion, coccidiosis control, and meat pigmentation improvement for more than 70 years. Most ROX is excreted in the litter and dispersed into the environment, where it is transformed by microbes into different arsenic-containing compounds. A major product of ROX transformation is N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA), which is also used as a clinical drug for treating refractory bacterial vaginosis. Here, we report the cloning and functional characterization of two genes encoding N-hydroxyarylamine O-acetyltransferases, NhoA1 and NhoA2, in Enterobacter sp. strain CZ-1, which catalyze the acetylation of 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) formed by the reduction of ROX to N-AHPAA. This study provides new insights into the function of N-hydroxyarylamine O-acetyltransferase in the transformation of an important organoarsenic compound.

scholarly journals Decreased Vancomycin Susceptibility in Staphylococcus aureus Caused by IS256Tempering of WalKR Expression

2013 ◽  
Vol 57 (7) ◽  
pp. 3240-3249 ◽  
Author(s):  
Christopher R. E. McEvoy ◽  
Brian Tsuji ◽  
Wei Gao ◽  
Torsten Seemann ◽  
Jessica L. Porter ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Fluorescent Protein ◽  
Site Directed Mutagenesis ◽  
Infection Model ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Phenotype Analysis ◽  
Dosing Regimens ◽  
Mrsa Strains ◽  
Green Fluorescent

ABSTRACTVancomycin-intermediateStaphylococcus aureus(VISA) strains often arise by mutations in the essential two-component regulatorwalKR; however their impact onwalKRfunction has not been definitively established. Here, we investigated 10 MRSA strains recovered serially after exposure of vancomycin-susceptibleS. aureus(VSSA) JKD6009 to simulated human vancomycin dosing regimens (500 mg to 4,000 mg every 12 h) using a 10-day hollow fiber infection model. After continued exposure to the vancomycin regimens, two isolates displayed reduced susceptibility to both vancomycin and daptomycin, developing independent IS256insertions in thewalKR5′ untranslated region (5′ UTR). Quantitative reverse transcription-PCR (RT-PCR) revealed a 50% reduction inwalKRgene expression in the IS256mutants compared to the VSSA parent. Green fluorescent protein (GFP) reporter analysis, promoter mapping, and site-directed mutagenesis confirmed these findings and showed that the IS256insertions had replaced two SigA-likewalKRpromoters with weaker, hybrid promoters. Removal of IS256reverted the phenotype to VSSA, showing that reduced expression of WalKR did induce the VISA phenotype. Analysis of selected WalKR-regulated autolysins revealed upregulation ofssaAbut no change in expression ofsakandsceDin both IS256mutants. Whole-genome sequencing of the two mutants revealed an additional IS256insertion withinagrCfor one mutant, and we confirmed that this mutation abolishedagrfunction. These data provide the first substantial analysis ofwalKRpromoter function and show that prolonged vancomycin exposure can result in VISA through an IS256-mediated reduction inwalKRexpression; however, the mechanisms by which this occurs remain to be determined.

scholarly journals The Gene Cluster forpara-Nitrophenol Catabolism Is Responsible for 2-Chloro-4-Nitrophenol Degradation in Burkholderia sp. Strain SJ98

2014 ◽  
Vol 80 (19) ◽  
pp. 6212-6222 ◽  
Author(s):  
Jun Min ◽  
Jun-Jie Zhang ◽  
Ning-Yi Zhou
Keyword(s):  
Gene Cluster ◽  
Gene Knockout ◽  
Gene Clusters ◽  
Sole Source ◽  
Pcr Analysis ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Biochemical Analyses ◽  
Nitrophenol Degradation

ABSTRACTBurkholderiasp. strain SJ98 (DSM 23195) utilizes 2-chloro-4-nitrophenol (2C4NP) orpara-nitrophenol (PNP) as a sole source of carbon and energy. Here, by genetic and biochemical analyses, a 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with chloro-1,4-benzoquinone (CBQ) as an intermediate. Reverse transcription-PCR analysis showed that all of thepnpgenes in thepnpABA1CDEFcluster were located in a single operon, which is significantly different from the genetic organization of all other previously reported PNP degradation gene clusters, in which the structural genes were located in three different operons. All of the Pnp proteins were purified to homogeneity as His-tagged proteins. PnpA, a PNP 4-monooxygenase, was found to be able to catalyze the monooxygenation of 2C4NP to CBQ. PnpB, a 1,4-benzoquinone reductase, has the ability to catalyze the reduction of CBQ to chlorohydroquinone. Moreover, PnpB is also able to enhance PnpA activityin vitroin the conversion of 2C4NP to CBQ. Genetic analyses indicated thatpnpAplays an essential role in the degradation of both 2C4NP and PNP by gene knockout and complementation. In addition to being responsible for the lower pathway of PNP catabolism, PnpCD, PnpE, and PnpF were also found to be likely involved in that of 2C4NP catabolism. These results indicated that the catabolism of 2C4NP and that of PNP share the same gene cluster in strain SJ98. These findings fill a gap in our understanding of the microbial degradation of 2C4NP at the molecular and biochemical levels.

scholarly journals Arr-cb Is a Rifampin Resistance Determinant Found Active or Cryptic in Clostridiumbolteae Strains

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Jean-Christophe Marvaud ◽  
Thierry Lambert
Keyword(s):  
Escherichia Coli ◽  
Gut Microbiota ◽  
Reverse Transcription ◽  
Recent Analysis ◽  
Pcr Analysis ◽  
Directed Mutagenesis ◽  
Human Gut ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Rifampin Resistance

ABSTRACT Clostridium bolteae, which belongs to the Clostridium clostridioforme complex, is a member of the human gut microbiota. Recent analysis of seven genomes of C. bolteae revealed the presence of an arr-like gene. Among these strains, only 90A7 was found to be resistant to rifampin in the absence of alteration of RpoB. Cloning of arr-cb from 90A7 in Escherichia coli combined with directed mutagenesis demonstrated that Arr-cb was functional but that a Q127→R variant present in 90A9 and 90B3 was inactive. Quantitative reverse transcription-PCR analysis indicated that arr-cb was silent in the four remaining strains because of defective transcription. Thus, two independent mechanisms can make the probably intrinsic arr-cb gene of C. bolteae cryptic.

scholarly journals Structure-Based Functional Characterization of Repressor of Toxin (Rot), a Central Regulator of Staphylococcus aureus Virulence

2014 ◽  
Vol 197 (1) ◽  
pp. 188-200 ◽  
Author(s):  
April Killikelly ◽  
Meredith A. Benson ◽  
Elizabeth A. Ohneck ◽  
Jared M. Sampson ◽  
Jean Jakoncic ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Dna Binding ◽  
Virulence Factors ◽  
Regulatory Networks ◽  
Functional Characterization ◽  
Site Directed Mutagenesis ◽  
Binding Motif ◽  
Content Type ◽  
Specific Effects ◽  
Target Promoters

Staphylococcus aureusis responsible for a large number of diverse infections worldwide. In order to support its pathogenic lifestyle,S. aureushas to regulate the expression of virulence factors in a coordinated fashion. One of the central regulators of theS. aureusvirulence regulatory networks is the transcription factor repressor of toxin (Rot). Rot plays a key role in regulatingS. aureusvirulence through activation or repression of promoters that control expression of a large number of critical virulence factors. However, the mechanism by which Rot mediates gene regulation has remained elusive. Here, we have determined the crystal structure of Rot and used this information to probe the contribution made by specific residues to Rot function. Rot was found to form a dimer, with each monomer harboring a winged helix-turn-helix (WHTH) DNA-binding motif. Despite an overall acidic pI, the asymmetric electrostatic charge profile suggests that Rot can orient the WHTH domain to bind DNA. Structure-based site-directed mutagenesis studies demonstrated that R91, at the tip of the wing, plays an important role in DNA binding, likely through interaction with the minor groove. We also found that Y66, predicted to bind within the major groove, contributes to Rot interaction with target promoters. Evaluation of Rot binding to different activated and repressed promoters revealed that certain mutations on Rot exhibit promoter-specific effects, suggesting for the first time that Rot differentially interacts with target promoters. This work provides insight into a precise mechanism by which Rot controls virulence factor regulation inS. aureus.

scholarly journals Expression Profiles and Functional Characterization of Chemosensory Protein 15 (HhalCSP15) in the Brown Marmorated Stink Bug Halyomorpha halys

2021 ◽  
Vol 12 ◽  
Author(s):  
Zehua Wang ◽  
Fan Yang ◽  
Ang Sun ◽  
Shuang Shan ◽  
Yongjun Zhang ◽  
...  
Keyword(s):  
Expression Profiles ◽  
Functional Characterization ◽  
Insect Species ◽  
Pcr Analysis ◽  
Halyomorpha Halys ◽  
Stink Bug ◽  
Stink Bugs ◽  
Binding Assays ◽  
Chemosensory Protein ◽  
Reverse Transcription Pcr

Chemosensory proteins (CSPs) have been identified in the sensory tissues of various insect species and are believed to be involved in chemical communication in insects. However, the physiological roles of CSPs in Halyomorpha halys, a highly invasive insect species, are rarely reported. Here, we focused on one of the antennal CSPs (HhalCSP15) and determined whether it was involved in olfactory perception. Reverse transcription PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) analysis showed that HhalCSP15 was enriched in nymph and male and female adult antennae, indicating its possible involvement in the chemosensory process. Fluorescence competitive binding assays revealed that three of 43 natural compounds showed binding abilities with HhalCSP15, including β-ionone (Ki=11.9±0.6μM), cis-3-hexen-1-yl benzoate (Ki=10.5±0.4μM), and methyl (2E,4E,6Z)-decatrienoate (EEZ-MDT; Ki=9.6±0.8μM). Docking analysis supported the experimental affinity for the three ligands. Additionally, the electrophysiological activities of the three ligands were further confirmed using electroantennography (EAG). EEZ-MDT is particularly interesting, as it serves as a kairomone when H. halys forages for host plants. We therefore conclude that HhalCSP15 might be involved in the detection of host-related volatiles. Our data provide a basis for further investigation of the physiological roles of CSPs in H. halys, and extend the olfactory function of CSPs in stink bugs.

scholarly journals γ-Resorcylate Catabolic-Pathway Genes in the Soil Actinomycete Rhodococcus jostii RHA1

2015 ◽  
Vol 81 (21) ◽  
pp. 7656-7665 ◽  
Author(s):  
Daisuke Kasai ◽  
Naoto Araki ◽  
Kota Motoi ◽  
Shota Yoshikawa ◽  
Toju Iino ◽  
...  
Keyword(s):  
Major Facilitator Superfamily ◽  
Pcr Analysis ◽  
Decarboxylase Activity ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Intergenic Regions ◽  
Major Facilitator Superfamily Transporter ◽  
Maleylacetate Reductase ◽  
Major Facilitator ◽  
Rhodococcus Jostii

ABSTRACTTheRhodococcus jostiiRHA1 gene cluster required for γ-resorcylate (GRA) catabolism was characterized. The cluster includestsdA,tsdB,tsdC,tsdD,tsdR,tsdT, andtsdX, which encode GRA decarboxylase, resorcinol 4-hydroxylase, hydroxyquinol 1,2-dioxygenase, maleylacetate reductase, an IclR-type regulator, a major facilitator superfamily transporter, and a putative hydrolase, respectively. ThetsdAgene conferred GRA decarboxylase activity onEscherichia coli. Purified TsdB oxidized NADH in the presence of resorcinol, suggesting thattsdBencodes a unique NADH-specific single-component resorcinol 4-hydroxylase. Mutations in eithertsdAortsdBresulted in growth deficiency on GRA. ThetsdCandtsdDgenes conferred hydroxyquinol 1,2-dioxygenase and maleylacetate reductase activities, respectively, onE. coli. Inactivation oftsdTsignificantly retarded the growth of RHA1 on GRA. The growth retardation was partially suppressed under acidic conditions, suggesting the involvement oftsdTin GRA uptake. Reverse transcription-PCR analysis revealed that thetsdgenes constitute three transcriptional units, thetsdBADCandtsdTXoperons andtsdR. Transcription of thetsdBADCandtsdTXoperons was induced during growth on GRA. Inactivation oftsdRderepressed transcription of thetsdBADCandtsdTXoperons in the absence of GRA, suggesting thattsdgene transcription is negatively regulated by thetsdR-encoded regulator. Binding of TsdR to thetsdR-tsdBandtsdT-tsdRintergenic regions was inhibited by the addition of GRA, indicating that GRA interacts with TsdR as an effector molecule.

scholarly journals The Two-Component GacS-GacA System ActivateslipATranslation by RsmE but Not RsmA in Pseudomonas protegens Pf-5

2014 ◽  
Vol 80 (21) ◽  
pp. 6627-6637 ◽  
Author(s):  
Daiming Zha ◽  
Li Xu ◽  
Houjin Zhang ◽  
Yunjun Yan
Keyword(s):  
Transcriptional Repression ◽  
Current Model ◽  
Ribosomal Subunit ◽  
Pcr Analysis ◽  
Signal Transduction System ◽  
Lipase Gene ◽  
Content Type ◽  
Homoserine Lactones ◽  
Reverse Transcription Pcr

ABSTRACTInPseudomonasspp., the Gac-Rsm signal transduction system is required for the production of lipases. The current model assumes that the system induces lipase gene transcription mediated through the quorum-sensing (QS) system. However, there are no reports of a QS system based uponN-acyl homoserine lactones or the regulation of lipase gene expression inPseudomonas protegens. In this study, we investigated the regulatory mechanism acting onlipAexpression activated by the Gac-Rsm system inP. protegensPf-5 through deletion and overexpression ofgacA, overexpression ofrsmAorrsmE, expression of variouslacZfusions, reverse transcription-PCR analysis, and determination of whole-cell lipase activity. The results demonstrated that the GacS-GacA (GacS/A) system activateslipAexpression at both the transcriptional and the translational levels but that the translational level is the key regulatory pathway. Further results showed that the activation oflipAtranslation by the GacS/A system is mediated through RsmE, which inhibitslipAtranslation by binding to the ACAAGGAUGU sequence overlapping the Shine-Dalgarno (SD) sequence oflipAmRNA to hinder the access of the 30S ribosomal subunit to the SD sequence. Moreover, the GacS/A system promoteslipAtranscription through the mediation of RsmA inhibitinglipAtranscription via an unknown pathway. Besides the transcriptional repression, RsmA mainly activateslipAtranslation by negatively regulatingrsmEtranslation. In summary, inP. protegensPf-5, the Gac-RsmE system mainly and directly activateslipAtranslation and the Gac-RsmA system indirectly enhanceslipAtranscription.

scholarly journals Functional Analysis of a Novel β-(1,3)-Glucanase from Corallococcus sp. Strain EGB Containing a Fascin-Like Module

2017 ◽  
Vol 83 (16) ◽  
Author(s):  
Jie Zhou ◽  
Zhoukun Li ◽  
Jiale Wu ◽  
Lifeng Li ◽  
Ding Li ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Functional Characterization ◽  
Hydrolytic Activity ◽  
Site Directed Mutagenesis ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Content Type ◽  
Binding Function ◽  
Catalytic Module

ABSTRACT A novel β-(1,3)-glucanase gene designated lamC, cloned from Corallococcus sp. strain EGB, contains a fascin-like module and a glycoside hydrolase family 16 (GH16) catalytic module. LamC displays broad hydrolytic activity toward various polysaccharides. Analysis of the hydrolytic products revealed that LamC is an exo-acting enzyme on β-(1,3)(1,3)- and β-(1,6)-linked glucan substrates and an endo-acting enzyme on β-(1,4)-linked glucan and xylan substrates. Site-directed mutagenesis of conserved catalytic Glu residues (E304A and E309A) demonstrated that these activities were derived from the same active site. Excision of the fascin-like module resulted in decreased activity toward β-(1,3)(1,3)-linked glucans. The carbohydrate-binding assay showed that the fascin-like module was a novel β-(1,3)-linked glucan-binding module. The functional characterization of the fascin-like module and catalytic module will help us better understand these enzymes and modules. IMPORTANCE In this report of a bacterial β-(1,3)(1,3)-glucanase containing a fascin-like module, we reveal the β-(1,3)(1,3)-glucan-binding function of the fascin-like module present in the N terminus of LamC. LamC displays exo-β-(1,3)/(1,6)-glucanase and endo-β-(1,4)-glucanase/xylanase activities with a single catalytic domain. Thus, LamC was identified as a novel member of the GH16 family.

Functional characterization and expression patterns of PnATX genes under different abiotic stress treatments in Populus

2020 ◽  
Vol 40 (4) ◽  
pp. 520-537
Author(s):  
Zhiru Xu ◽  
Jiahuan Huang ◽  
Chunpu Qu ◽  
Ruhui Chang ◽  
Jinyuan Chen ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Metal Binding ◽  
Molecular Mechanisms ◽  
Expression Patterns ◽  
Functional Characterization ◽  
Pcr Analysis ◽  
Binding Motif ◽  
Copper Chaperone ◽  
Specific Expression ◽  
Relative Expression Level

Abstract The copper chaperone ATX1 has been investigated previously in the herbaceous plants Arabidopsis and rice. However, the molecular mechanisms of ATX1 underlying copper transport and functional characteristics in the woody plant Populus are poorly understood. In this study, PnATX1 and PnATX2 of Populus simonii × P. nigra were identified and characterized. Sequence analysis showed that PnATXs contained the metal-binding motif MXCXXC in the N-terminus and a lysine-rich region. Phylogenetic analysis of ATX protein sequences revealed that PnATXs were clustered in the same group as AtATX1. PnATX proteins were localized in the cytoplasm and nucleus. Tissue-specific expression analysis showed that PnATX1 and PnATX2 were expressed in all analyzed tissues and, in particular, expressed to a higher relative expression level in young leaves. Quantitative real-time PCR analysis indicated that each PnATX gene was differentially expressed in different tissues under treatments with copper, zinc, iron, jasmonate and salicylic acid (SA). The copper-response element GTAC, methyl jasmonate and salicylic acid responsiveness elements and other cis-acting elements were identified in the PnATX1 and PnATX2 promoters. Expression of β-glucuronidase driven by the PnATX1 promoter was observed in the apical meristem of 7-day-old Arabidopsis transgenic seedlings, and the signal strength was not influenced by deficient or excessive copper conditions. Both PnATX1 and PnATX2 functionally rescued the defective phenotypes of yeast atx1Δ and sod1Δ strains. Under copper excess and deficiency conditions, transgenic Arabidopsis atx1 mutants harboring 35S::PnATX constructs exhibited root length and fresh weight similar to those of the wild type and higher than those of Arabidopsis atx1 mutants. Superoxide dismutase activity decreased in transgenic lines compared with that of atx1 mutants, whereas peroxidase and catalase activities increased significantly under excess copper. The results provide a basis for elucidating the role of Populus PnATX genes in copper homeostasis.

scholarly journals The CRISPR-Associated Gene cas2 of Legionella pneumophila Is Required for Intracellular Infection of Amoebae

mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Felizza F. Gunderson ◽  
Nicholas P. Cianciotto
Keyword(s):  
Reverse Transcription ◽  
Legionella Pneumophila ◽  
Host Cells ◽  
Pcr Analysis ◽  
Rt Pcr ◽  
Content Type ◽  
Intracellular Infection ◽  
Reverse Transcription Pcr ◽  
Crispr Array ◽  
Agar Media

ABSTRACTRecent studies have shown that the clustered regularly interspaced palindromic repeats (CRISPR) array and its associated (cas) genes can play a key role in bacterial immunity against phage and plasmids. Upon analysis of theLegionella pneumophilastrain 130b chromosome, we detected a subtype II-B CRISPR-Cas locus that containscas9,cas1,cas2,cas4, and an array with 60 repeats and 58 unique spacers. Reverse transcription (RT)-PCR analysis demonstrated that the entire CRISPR-Cas locus is expressed during 130b extracellular growth in both rich and minimal media as well as during intracellular infection of macrophages and aquatic amoebae. Quantitative reverse transcription-PCR (RT-PCR) further showed that the levels ofcastranscripts, especially those ofcas1andcas2, are elevated during intracellular growth relative to exponential-phase growth in broth. Mutants lacking components of the CRISPR-Cas locus were made and found to grow normally in broth and on agar media.cas9,cas1,cas4, and CRISPR array mutants also grew normally in macrophages and amoebae. However,cas2mutants, although they grew typically in macrophages, were significantly impaired for infection of bothHartmannellaandAcanthamoebaspecies. A complementedcas2mutant infected the amoebae at wild-type levels, confirming thatcas2is required for intracellular infection of these host cells.IMPORTANCEGiven that infection of amoebae is critical forL. pneumophilapersistence in water systems, our data indicate thatcas2has a role in the transmission of Legionnaires’ disease. Because our experiments were done in the absence of added phage, plasmid, or nucleic acid, the event that is facilitated by Cas2 is uniquely distinct from current dogma concerning CRISPR-Cas function.

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